Here's something else that we need to notice about Haman: he did what the king asked him to do, but it didn't change his heart...and he didn't require it to.
A lot of times, we let ourselves off the hook because we think that if God really wanted us to do something - even something like "love your neighbor," which He already clearly told us to do - then He will change our heart and give us the kind of heart that makes such a thing easy for us. He'll make us want to do whatever it is that He's asking us to do.
Anyone who has lived the life of faith long enough will tell you...nope. God does not always make you want to do what He wants you to do, and He certainly doesn't always make it easy. What God does is He makes you want to want whatever He wants, which is better anyway.
The king didn't tell Haman a story about Mordecai. At least, we aren't told that he did. We aren't told that the king told Haman anything about Mordecai except to honor him. So Haman got absolutely zero new data to re-evaluate his beliefs about Mordecai except perhaps for the data point that now, this Jew - this despicable Jew - was taking the honor that Haman thought was due to himself.
That's certainly not going to help Haman's heart.
But again, it didn't have to.
Haman doesn't have to love Mordecai. He doesn't have to agree with the king's perception of the man. He doesn't have to reconsider his position at all. He doesn't have to let go of the bitterness in his heart. He doesn't have to share the king's opinion of Mordecai in the slightest to do what the king has told him to do. Not at all.
Of course, yes, in an ideal world, he does change his heart. In an ideal world, he does see Mordecai through new eyes. In an ideal world, he does let go of his prejudices, at least long enough to allow something new to flicker in front of his eyes. But I think this takes something more than mere obedience. And the point of our conversation here and now is that we should not overlook the power, the beauty, the goodness in something so simple as obedience.
The same is true of our walk with God. Yes, in an ideal world, walking with God changes our heart. In an ideal world, we grow into new persons the more we hang around Him and do what He asks us to do. We do see with new eyes the things that He's trying to show us. But again, that takes something more than mere obedience.
Also again, mere obedience is a great place to start.
So if you're waiting on God to change your heart, stop waiting. Just obey. Just do what God is asking you to do. Yes, hopefully, it changes your heart when you do what God asks you to do, but let us not overlook doing - in earnest (Haman acted earnestly in his obedience to the king) - it anyway. Just obeying. Just following the King's command. That is such a huge thing, really. So...start there.